Function makeCheapPathFunction

tools/fs/optimistic.ts:225–251

(
  pathFunction: (path: string) => TResult,
)

}

function makeCheapPathFunction<TResult>(
  pathFunction: (path: string) => TResult,
): typeof pathFunction {
  if (! ENABLED) {
    return pathFunction;
  }
  const wrapper = wrap(pathFunction, {
    // The maximum LRU cache size is Math.pow(2, 16) by default, but it's
    // important to prevent eviction churn for very-frequently-called
    // functions like optimisticStatOrNull. While it's tempting to set
    // this limit to Infinity, increasing it by 16x comes close enough.
    max: Math.pow(2, 20),
    subscribe(path) {
      let watcher: SafeWatcher | null = watch(
        path,
        () => wrapper.dirty(path),
      );
      return function () {
        if (watcher) {
          watcher.close();
          watcher = null;
        }
      };
    }
  });
  return wrapper;
}

export const optimisticStatOrNull = makeCheapPathFunction(
  (path: string) => {